Passive anti-theft systems (“PAT systems”) for vehicles are well known. Typical PAT systems prevent the engine from being started unless at least two general conditions are satisfied. First, the driver must utilize a key having a structure properly configured for turning the cylinder lock of the ignition. Second, the key must also have an identification (“ID”), which matches an ID stored within an electronic control module (“ECM”) of the PAT system. In this way, the typical PAT system provides additional security to conventional lock-and-key ignition devices.
The ECM normally learns a key by writing a unique secret code to both the ECM and the key. As is known, this unique secret code is utilized with an encryption algorithm for allowing the ECM and the key to communicate with each other for the purpose of allowing the ECM to authenticate the key. It is also understood that once a typical key is written to, the key is permanently locked and cannot be overwritten.
A drawback of existing ECMs is that they usually are incapable of re-learning a previously programmed key. Specifically, it is understood that on occasion the key's ID, the unique secret code associated with that key, or any combination thereof may have been erased or otherwise disabled in the ECM's memory. For that reason, the ECM cannot recognize the key or communicate with the key for authentication purposes. Moreover, since the key cannot be re-written or re-programmed, the key may be wasted thereby requiring a new unprogrammed key to be purchased and learned by the ECM. Such a result can be somewhat expensive and time-consuming.
Therefore, a need exists for a method and system for re-learning a previously programmed key for allowing the continued use of that key.